Production of sodium-carbonate liquor



Fab"; 3, 1;"'9'3l. H. w. MORSE 1,791,281

PRODUCTIQN OF SODIUM CARBONATE LIQUOR Fil ed April 29 1929 Vacuum 7% I Sefl/er f6." V Z] I fixlsp/acema /vf Was/7 I flow/y Wbee/c'r Morse g hxis Elbtomuf 23 I I I 6/20/11 I Patented Feb. 3,1931 i 3 1391231;

I uurrsn s'rarss PATENT OFFICE HARRY WHEELER Mensa, or annwoon' CITY, CALIFORNIA PRODUCTION OF SODiUM-CARBONATE LIQUOR i Applicati on filed April 29, 1929. Serial No. 359,109.

This invention relatesto the recovery of tails salts produced in any one pan will be sodium carbonate from waste salts containing different from that produced in the other this salt, and in particular to its recovery pans, the high temperature pan yielding a from the tails salts produced inthe treatment product of the following typical composiof Searles Lake brine. tion: I 55 It is an object of this invention to provide I I Per cent a process by which the sodium carbonate may sodlllm mmt fl' 16. 0 be economically and easily separated from W- Sulfate 14. 0 Sodium chloride o 68.0

waste salts containing the same. A further object is to provide a process for recovering sodium carbonate from Searles Lake brine tails salts, without affecting-the recovery of the valuable potassium salts and borax contained inthe brine. d

Other objects will appear as the description proceeds. I I

During the evaporation of Searles Lake Of, the sodium carbonate present in this 60 mixture,6 to ti of the weight of the tails salts is present as the.doublesulfate-carbonate, while 9 1O% is present as free sodium carbonate. I I

. If tails salts produced in either of the foregoing ways are washed with water at a tembrine in multiple efiect evaporatoraiclystal- P i of v sodlum Carbonate line solids (generally called tails salts) sepreitchly dlsioived therefrom t arate which contain principally the chloride, solutlon contmnmg up to 12% of Sodmm 79 sulfate and carbonate of sodium together a together wlthv.sodm.m chloride a with small amounts of other substances. If Sodlum l Workmg Wlth the tans Salts the'brine is evaporated without pretreatment g t f g fi those from untreatid of any'kind, the average tails saltswhich sepi bthat slodlum Carbonate equal 111 Y arate during evaporation may have the foli 1t to out of the Welght 9 the lowing approximate and typical composi tails salts, may be dissolved; 1f saltsfrom tion: I pretreated br ne are so treated, sodium car- I I Per nt bonate equal 1n weight to about 12% of the Sodiun carbonate 12, 5 Weight Of the tails salts be CllSS0lVed. if s di lf t 210, I The solution. of sodium, carbonate thus S di hl id 65,0 prepared will contain from 8 to 12% of soi I dium carbonate, and is a valuable raw mate- Of the total sodium carbonate present in rialfor the manufacture either of pure sothese solids, 7 8% of the weight of the tails dium carbonate, or as a raw material for the Y salts is in combination with sodium sulfate manufacture ofcaustic soda. Inasmuch as .as a double salt; the remaining l -5 being those tails salts have always been regarded present in the free state. as waste by products, and have been cus- In my co-pending application, Serial No. tomarily discarded as worthless, it is ap- 351,331, filed March 30, 1929, I disclose a parent that my invention furnishes a very process for treating Searles Lake brine. This cheap source of sodium carbonateliquor and Y process comprises the addition to raw brine of extracts a useful product from a hitherto solid tails salts from a previous portion of practically useless one. 7 brine. After adding these salts to raw brine, he total quantity-of'tails salts producedi's and agitating at 90100 C. for a time, withquite large compared with the quantity of 4,5 out evaporation, nearly pure sulfate-carbonpotassium chloride and borax produced in the ate of soda separates in solid form. operation, and if: eflicient frecovery of' the If now, brine which has been thus pref potassium chloride and hora-X of the brine is treated, is evaporated in a multiple effect to beattained,the tails salts must berather p evaporator, tails salts will of course separate carefully washed free of adhering concenin each pan. The average composition of the trated liquor. This washing is best per--15;

formed by the use of raw brine, and the wash liquor so produced is added to the main brine feed of the evaporating system, thus returning to the system the potassium chloride and the boraX.

I have found that following the raw brine wash, it is possible to recover a large part of the sodium carbonate'of the tails salts by merely giving them a spray wash with fresh water. In this manner, I have been able to recover about 50% ofthe sodium carbonate from the tails salts of untreated brine, and about 7 of the sodium carbonate from the tails salts of a pretreated brine.

One method of carrying out my invention is illustrated in the accompanying sheet of drawings, in which the single figure represents a side elevation, partly in section, of apparatus particularly adapted to carry out said process.

l have shown generally at 10 a vacuum pan which may be one unit of a multiple effect system. Brine, either pretreated or untreated, may be fed into the pan through intake pipe 12 which I have shown as feeding into the L-shape conduit 1%. This latter conduit taps into the bottom of the chamber 16 of the vacuum pan, and feeds at its lower end into a rotary pump 18. Pump 18 is thus adapted to draw liquid material from conduit 1 1 and discharge it through tubes 20 back into the chamber 16. A jacket 22 surrounds tubes 20, forming, together with tube sheets 21, a casingenclosing the tubes 20 to which steam is admitted through a steam inlet 24 for heat ing the liquid as it is forced through tubes 20.

Condensate may be removed from the casing through pipe 26. The water vapor is removed from the vacuum pan through a pipe 27 which is connected to a suitable vacuum system not shown.

A settling tank, indicated conventionally at 28, is connected .with evaporator 10 through conduit 30. This settling tank may also be operated under a vacuum; a pipe 32, tapping into both settler and evaporator provides means for equalizing the pressure between the two. A return conduit 34 having a valve 36 provides means for optionally returning the clear, supernatant liquid from the settling tank back into the evaporator. An outlet pipe 38 is also provided for dran ing off the clear liquid from the settler.

The tails salts which separate in. settler 28 are transferred in the form of a sludge through conduit 40 to the pan 42 of a conventional type of vacuum filter. The drum of this filter operates in the direction indicated by the arrow. I

vOn the first section of the filter drum, indicated at 44, the residual brine is removed from the sludge of tails salts, and the salts are sucked as dry as practicable. Themother liquo r filtrate withdrawn throughpipe 46, and is returned. to the evaporating system;

dissolve the sodium carbonate as explained above.

The fresh water with sodium carbonate in solution, is withdrawn through pipe 56. The sodium carbonate thus recovered may, of course, be used as desired. For example, the solution could be used directly after concentration for the production of other sodium compounds, such as caustic soda. ihe residual salts are scraped off the filter drum at 60, and are discarded.

While I have described a particular arrangement of apparatus, which I have found well adapted to carrying out my process, it must be understood that I do not limit my self thereto. Many changes in the details of operation would appear as obvious to anyone skilled in the art, and these changes are to be considered as comprised in my invention. I wish to be limited only by the prior art and the scope of the appended claims.

I claim:

1. A process for recovering sodium carbonate from tails salts containing the same, comprising washing said tails salts with water at a temperature of from to C. 2. A process for the recovery'of sodium carbonate from Searles Lake brine, comprising evaporating said brine to cause a precipitation of tails salts, separating said tails salts from said partially evaporated brine, washing said tails salts with raw brine to remove the evaporated brine therefrom, and subsequently treating said washed tails salts with water at a temperature of 30 to 10 C. to dissolve out sodium carbonate from said tails salts.

In testimony whereof, I have signed my name to this specification.

HARRY WHEELER MORSE.

As the salts 

